Technically speaking, Jack doesn't work in the library anymore. He's actually making... sort-of decent money publishing his own work now. It wouldn't be enough to live on if he had to pay actual rent or something, but since all his meals, utilities, and costs of living are covered by the castle, every bit of income he makes is surplus and can be stored away.

He just... really loves books, and finds himself gravitating to the library whenever he has free time. Normally he'd be perfectly content being an introvert and leaving everyone absolutely the hell alone to mind his own business, but seeing a new face get battered by books is almost as sad as seeing books hitting the floor like that, so...

Yeah. He steps in. Unobtrusively, customer-service polite, with a muted little wave.

"Hey. Sorry, I um... I used to work here, if you need... help figuring out the shelving system."